1. Field of the Invention
The present invention relates to an actuator and, more particularly, to an actuator using an electromechanical energy conversion element.
2. Description of the Related Art
Various actuators which use electromechanical energy conversion elements as piezoelectric elements are proposed. For example, the present applicant has developed an actuator which is driven in two directions using one piezoelectric element. The contents of this invention were filed in Japanese Patent Application No. 9-11424 in Japanese Patent Office.
The piezoelectric actuator, described in Japanese Patent Application No. 9-11424, in which a vibrator is vibrated by applying a pulse voltage to one piezoelectric element to make it possible to move a movable member which is in press contact with the vibrator, comprises: a pulse control circuit for selectively making it possible to apply a first pulse voltage to the piezoelectric element to cause the vibrator to generate a vibration having a first resonance frequency, or apply a second pulse voltage to the piezoelectric element to cause the vibrator to generate a vibration having a second resonance frequency, and a drive transmission means for transmitting the generated vibration to the movable means such that the movable means is driven in a first direction when the vibration having the first resonance frequency is generated, and the movable means is driven in a second direction when the vibration having the second resonance frequency is generated.
In the actuator described in Japanese Patent Application No. 9-11424, an embodiment is proposed in which there is a means for holding a vibrator and a member to be driven, and a means for pressing the vibrator and the member to be driven. However, these proposed elements are not described. It is difficult to actually design the actuator of that embodiment.